Checks for uninitialized access to calldata variables.

test/libsolidity/syntaxTests/controlFlow/localCalldataVariables/if_declaration_err.sol

@@ -0,0 +1,10 @@
+contract C {
+    function f(uint[] calldata _c) public pure {
+        uint[] calldata c;
+        if (_c[2] > 10)
+            c = _c;
+        c[2];
+    }
+}
+// ----
+// TypeError: (141-142): This variable is of calldata pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.